61Surgical resection of previously radiated
tumors carries increased risk of neurovascular
injury. At all times sharp dissection is preferred
to blunt dissection in order to avoid unintended
traction on neurovascular structures. The use of
an ultrasonic aspiration device allows rapid deb-
ulking, but should be used carefully as large
tumors can engulf cranial nerves and arteries.
The tandem use of an endoscope and microscope
has proven to be of tremendous value in increas-
ing the extent of resection while minimizing
complications [ 15 ].
Closure
Closing the dura following this approach often
requires a duraplasty. After securing the graft in
place, strips of the fat graft harvested from the
abdomen are placed in the region of the cavern-
ous sinus and used to obliterate any exposed air
cells including the mastoid cavity. The previ-
ously preserved pedicled temporalis fascia is
rotated such that it lies along the floor of the
middle cranial fossa and covers the mastoid cav-
ity and secured in place with sutures (Fig. 4.5).
The mastoid cortex is plated in anatomical posi-
tion using titanium plating along with the
remainder of the craniotomy flap. Hydroxyapatite
is used to fill in any remaining defects and cover
implanted hardware such that it would not be
palpable by the patient. If osteotomies were
made along the zygomatic arch, it is plated. The
temporalis muscle is re-suspended in anatomic
position using sutures. The galea and subse-
quently the skin are closed in layers in the usual
fashion. A sterile dressing is applied, along with
a head-wrap (Fig. 4.6).Tricks and Pitfalls
There are a number of surgical precautions that
should be followed for the safe execution of the
posterior and combined petrosal approaches. The
chief concern is the patient’s particular variations
of the venous anatomy surrounding the Labbe
complex, petrosal complex, and basal temporal
and occipital venous complexes. The point of
insertion of the vein of Labbe, which may be
multiple, should be well understood in advance
of surgery such that the tentorial cut can be
planned rostral to that location. Certain variants,
such as the presence of a dominant venous chan-
nel within the tentorium, may absolutely contra-
indicate an approach involving cutting the
tentorium. Others, such as the presence of a sin-
gle sigmoid sinus ipsilateral to the tumor, require
particular attention to avoid thrombosis or injury
to the sinus.
With large musculocutaneous flaps, extensive
bone drilling, and intradural exposure of multi-
ple CSF cisterns comes increased risk for pseu-
domeningocele formation and spinal fluid leak.
This risk is mitigated by conforming to a meticu-
lous multilayered closure that takes advantage of
a well-vascularized, pedicled temporalis flap.
Dural closure frequently requires the use of a
dural graft. Fat is used generously to obliterate
exposed air cells, but the use of large uncut
pieces is avoided in order to reduce the risk of fat
necrosis [ 16 ]. Cranioplasty, by replacing all
removed bone including the mastoid cortex, also
reduces the risk of leak and improves cosmetic
outcomes [ 17 ].Fig. 4.5 Closure. The previously reserved pedicled tem-
poralis fascia is placed along the floor of the middle fossa
and secured with suture, clips and/or fibrin glue
(Reproduced with permission from Al-Mefty [ 18 ])
4 Posterior and Combined Petrosal Approaches